Synthesis And Characterization Of Binary And Ternary Complexes For Rare Earth With 2- Thiophencarboxylic Acid And 2, 2'-Bipyradine And Studies On Fluorescence Spectra Of Complexes

Ten solid binary complexes of rare earth perchlorate with 2-thiophene carboxylic acid(L) and foure ternary complexes of rare earth perchlorate with 2-thiophene carboxylic acid(L)-2,2'-bipyridine(L )have been synthesized.By elecmental analysis,rare earth coordination titration and DTG studies.the composition of the complexes were suggested as REL₃·2H₂O(RE=Y,La,Pr,Nd,Sm,Eu,Gd,Tb,Dy, Er) and REL₃L'·C₂H₅OH(RE=Sm,Eu,Tb,Dy) respectively.IR spectra and 1HNMR studies indicate that the ligands coordinate with rare earth by the oxygen atoms of 2-thiophene carboxylic acid and nitrogen atoms of 2-2'-bipyridine .The Molar conductivities in DMF solvent indicate that the complex are nonelectrolyte. Fluoresence spectra of Eu³⁺ and Tb³⁺ complexes show that ligands have a strong sensitization effect on fluorescence of Eu³⁺.Otherwise,the fluorescence emission intensity of ternary complexes have been enhanced strongly by 2,2'-bipyridine in mixing.The results show that the triplet state energy of the ligand is most matching with the excitated state energy of rare earth ions.